1. Field of the Invention
This invention relates in general to production of oil and gas wells, and in particular to a system for maintaining a threaded connection between tubulars.
2. Description of the Related Art
Oil and gas wells typically include tubular strings that extend into the well in conjunction with drilling, casing, and production operations. The strings are made up as they are inserted into the well by using connectors to join discrete segments of pipe. Pipe connectors usually include a male portion having one end that connects to a pipe segment, and an opposite end with male threads, which is referred to as a pin. Connectors also include a female portion, which has an end to another pipe segment, and an opposite end with female threads, which is commonly referred to as a box. Thus threading the box into the pin couples together the pipe segments. Once the pipe segments are joined, relative rotation between the male and female connectors is limited to ensure they remain firmly attached. Locking systems are sometimes employed for limiting circumferential movement between male and female connectors.
Some known locking systems include keys that insert into corresponding grooves in the pin and the box that align when the pin and the box are threaded together. However, because proper sealing requires fully torqueing the pipe connectors, manufacturing tolerances and variances in loading negatively affect repeatability of azimuthal alignment of adjacent connectors. Additionally, some threaded connectors have small overall wall thickness (e.g., subsea drill pipe and casing), thereby requiring a key that is low profile. Furthermore, space limitations prohibit use of some keys that require large devices to drive locking pins or keys into place.